This invention relates to folded fastening assemblies and method and apparatus for producing and applying the fastening assemblies.
Fastening assemblies that carry hooks or loops are desirable as part of infant and adult diapers, surgical gowns, and other garments and wraps. Fastening assemblies typically comprise a flexible sheet-form film or non-woven web, that has a tab for connecting to an object and a tape of fastener hook elements secured to a surface of the web, forming a laminate structure. The tab of the fastening assembly is attached to one side of an object and the fastener tape is free to engage a hook-engageable surface formed on an opposite side of the object. The fastener tape is typically made of a synthetic resin that is not stretchable, and the resulting laminate is relatively stiff, does not stretch, and does not present the desired degree of cloth-like feel.
Fastening assemblies are often formed by laminating the sheet form film or web with a fastener tape and forming a tab for connecting to an object. One typical application for such fastener tabs is for diaper closure systems. The diaper is generally sold with one end of the fastener tab pre-attached to one of the sides of the diaper and the other end of the fastener tab releasably attachable to the other side of the diaper for securing the diaper around a baby.
It is desirable to provide an economical method of forming fastening assemblies that have a tab and a fastener tape. It is also desirable to provide such assemblies having integral components that achieve desired qualities, such as elasticity, flexibility and low cost and ability to be employed in existing automated assembly systems, such as systems for mass-produced diapers.
According to one aspect of the invention, a method of forming a fastening product is provided. The fastener product has a multiplicity of fastener elements extending from a strip-form base, the base including first and second attachment members for attachment of a substrate therebetween. The method includes continuously introducing molten resin to a gap defined adjacent a peripheral surface of a rotating mold roll, such that the resin forms part of the strip-form base of the product at the peripheral mold roll surface and fills an array of fixed cavities defined in the rotating mold roll to form portions of the fastener elements as projections extending from a first side of the sheet-form base. The method also includes introducing to the resin on the mold roll a sheet material folded about a longitudinal fold line to form first and second overlapping fold portions, the sheet material introduced under conditions selected to cause the second fold portion to become permanently bonded to resin of the base, while leaving the first fold portion free to be subsequently unfolded from the second fold portion about the fold line. The resin is solidified and stripped from the peripheral surface of the mold roll by pulling the projections from their respective cavities.
Variations of this aspect of the invention can include one or more of the following features. The folded material is folded about multiple fold lines separating more than two fold members. The second fold portion is bonded to the first side of the base from which the fastener elements extend. The second fold portion is bonded to a second side of the base opposite the first side from which the fastener elements extend.
In another aspect of the invention a method of forming a fastening assembly includes molding a continuous sheet-form base having a multiplicity of fastener elements integrally molded with and extending from a fastening section of a surface of the base lying generally in a plane. The base, as molded, has a non-planar undulation in which the base extends out of its plane to form a peak that extends along a longitudinal direction of the base with opposite major surfaces of the base remaining generally parallel. The undulation is elastically deformable to enable the base to stretch laterally upon application of a lateral tensile force to the fastener product.
Variations of this aspect of the invention can include one or more of the following features. The base, as molded, has multiple, parallel undulations, each undulation forming a peak. The undulations are disposed in a region adjacent the fastener elements. The undulations are molded integrally with the fastener section. The undulation is formed by a mating groove and channel of a pair of rolls defining a nip in which the base is formed. The undulation is pre-formed on a material that is introduced into a base-forming nip formed by a pair of rolls; the rolls having a mating groove and channel that accommodate the undulation.
Other variations can include coating the undulation with an elastomer and/or filling an area between adjacent peaks with an elastomer. The elastomer is selected from the group consisting of thermoplastic elastomers, thermoplastic polyurethanes, elastomeric copolymers containing polyethylene terephthalate PET, thermoplastic olefins, and natural or synthetic rubber. The fastener section is molded of resin selected from the group consisting of polyester, polyethylene, polypropylene, polyamide and copolymers and alloys thereof. The method includes forming a tab joined with the base, the tab extending laterally from the undulation along a lateral margin of the fastener assembly opposite a second lateral margin more nearly adjacent the fastening section, the tab comprising at least one flap for joining the fastener assembly to an article. The flap is formed of a section of the base molded integrally with and of the same resin as the portion having the undulation and the fastening section. The flap is formed by folding and permanently joining a portion of the base to another portion of the base. The portion of the base that is folded is thinner than other portions of the base. The Tab is formed by introducing a sheet material into a nip in which the base is molded, the sheet material being folded about a longitudinal fold line to form first and second overlapping fold portions and introduced under conditions selected to cause the second fold portion to become permanently bonded to resin of the base, while leaving the first fold portion free to be subsequently unfolded from the second fold portion about the fold line. The sheet material is bonded to a surface of the base opposite the first surface from which the fastener elements extend. The sheet material is bonded to the first surface of the base from which the fastener elements extend. The second fold portion is bonded to the base only along a margin area of an exposed surface of the second fold portion. Unbonded surface areas of the first and second fold portions are protected from contact with the resin by a protective tape forming a barrier to the resin. Unbonded surface areas of the first and second fold portions are protected from contact with the resin by a protective coating forming a barrier to the resin. The method includes forming dams along edges of the fastening section. The dams are higher than the fastener elements. The step of permanently joining is achieved by heat staking, adhesive or rf-welding together the portion of the base to another portion of the base.
In another aspect of the invention, a method of forming fastener tabs, each tab including a multiplicity of fastener elements extending from a strip-form base and first and second attachment legs for attaching the tab to a garment or substrate therebetween, is disclosed. The method includes continuously introducing molten resin to a gap defined adjacent a peripheral surface of a rotating mold roll, such that the resin forms at least a part of the strip-form base of the product at the peripheral mold roll surface and fills an array of fixed cavities defined in the rotating mold roll to form portions of the fastener elements as projections extending from a first side of the sheet-form base; while introducing a pre-formed material to the resin under conditions selected to cause a portion of the resin to become permanently bonded to the pre-formed material, the preformed material forming at least a part of the strip-form base of the product. The resin is solidified and stripped from the peripheral surface of the mold roll by pulling the projections from their respective cavities. The method further includes folding a portion of the strip-form base to form the first and second attachment legs.
This aspect of the invention can include any of the variation mentioned herein with respect to other aspects of the invention.
In another aspect, the invention is a method of forming fastener tabs, each tab including a multiplicity of fastener elements extending from a strip-form base and first and second attachment legs for attaching the tab to a garment or substrate therebetween. The method includes continuously introducing molten resin to a gap defined adjacent a peripheral surface of a rotating mold roll, such that the resin forms at least a part of the strip-form base of the product at the peripheral mold roll surface and fills an array of cavities defined in the rotating mold roll to form portions of the fastener elements as projections extending from a first side of the sheet-form base. The resin is solidified and stripped from the peripheral surface of the mold roll by pulling the projections from their respective cavities. The method further includes folding a portion of the strip-form base to form the first and second attachment legs.
Variations of this aspect of the invention can include any of the variations mentioned herein with respect to other aspects of the invention.
In another aspect of the invention, a fastening assembly is provided. The fastening assembly includes a multiplicity of fastener elements integrally molded with and extending from a first surface of a sheet-form base to form a fastening section of the fastening assembly, and a spring section integrally molded with and extending laterally from the fastening section, the spring section formed by at least one undulation of the sheet form base that allows the spring section to stretch elastically in a lateral direction upon application of lateral tension to the fastening assembly.
Variations of this aspect of the invention can include one or more of the following features. The undulation is coated with an elastomeric resin. The undulation is triangular. The undulation is sinusoidal. The fastening assembly further includes a tab section having a first and a second attachment leg.
In another aspect, the invention provides a fastener tab including a continuous, unitary strip of thermoplastic resin having first and second end regions, a multiplicity of fastener elements, each having a stem integrally molded with and extending from a surface of the unitary strip disposed in the first end region, and the second end region having two opposable leg portions formed integrally with and of the same material as the continuous strip, the two opposable leg portions positioned to be secured to oppositely directed faces of a substrate or article to support the tab in a manner that the first end may be free to enable its fastener elements to engage a mating surface.
Variations of this aspect of the invention can include one or more of the following features. The leg portions extend from a common hinge region. The strip of thermoplastic resin has a longitudinal profile configured to define at least one hinge region. The hinge region is defined by a localized reduction in thickness of the strip of thermoplastic resin. Portions of the strip of thermoplastic resin are folded together and permanently joined to define the two leg portions. The continuous strip of thermoplastic resin has at least two spaced apart-localized lines of reduced thickness extending longitudinally across the strip to define two hinge regions about which adjacent portions of the strip are folded to constitute the leg portions. The strip, as initially formed, has a substantially longitudinal straight profile with a first hinge region spaced from its adjacent end a first distance and a second hinge region spaced from the end a substantially greater distance, the strip having been bent back upon itself about the second hinge, the bent back portion being permanently joined to the remainder of the strip adjacent to the first hinge region, the outer portion of the strip being free to bend about the first hinge to form an attachment jaw for receiving therebetween a substrate or article to which the oppositely directed surfaces of the respective leg portions may be joined. The bent back portion is permanently joined to the remainder of the strip by adhesive. The bent back portion is permanently joined to the remainder of the strip by ultrasonic bonding. The bent back portion is permanently joined to the remainder of the strip by heat staking.
In another aspect the invention provides a fastener tab. The fastener tab includes a strip form, unitary body consisting essentially of a contiguous resin, the body having a first end and a second end, hooks in a first end region, and two opposable legs in a second end region spaced apart from the hooks for mounting the fastener tab to opposite sides of a substrate.
Variations of this aspect of the invention can include one or more of the following features. The second end region includes a first portion, a second portion, and a hinge therebetween. The second end region is folded about the hinge to overlap the first portion and the second portion. The fastener tab further includes at least one of an adhesive, an ultrasonic weld or a heat stake, joining the overlapped first and second portions. The hinge is defined by a section of decreased thickness. The second region further includes a third portion and a second hinge between the second portion and the third portion. The first portion extends generally in a plane defined by the first end region, and the second portion is folded back over the first portion. The first portion extends out of a plane defined by the first end region, and the second portion is folded back over the first portion. One of the two opposable legs comprises an integrally molded portion extending out of a plane defined by the first end region. The second end region includes a first portion extending generally in a plane defined by the first end region, a second portion folded back over the first portion, and a third portion folded back over the second portion. The second portion forms a first of the two opposable legs, and the third portion forms a second of the two opposable legs. The first and second portions are permanently joined by one of adhesive, heat staking, and ultrasonic welding. The body defines a hinge located between the first portion and the second portion. The body defines a hinge located between the second portion and the third portion. The second end region includes a first portion extending out of a plane defined by the first end region, a second portion folded back over the first portion, and a third portion extending generally in the plane defined by the first end region. The third portion forms a first of the two opposed legs, and the second portion forms a second of the two opposed legs. The first and second portions are permanently joined by one of adhesive, heat staking, and ultrasonic welding. Each of the two opposed legs has an inner facing surface including an adhesive. The adhesive includes a pressure sensitive adhesive. The body is formed of a thermoplastic synthetic resin. The resin includes polypropylene.
In another aspect, the invention provides a roll of fastener tabs joined side-to-side. Each fastener tab includes a strip form, unitary body consisting essentially of a contiguous resin, the body having a first end and a second end, hooks in a first end region, and two opposable legs in a second end region spaced apart from the hooks for mounting the fastener tab to opposite sides of a substrate.
Variations of this aspect of the invention can include one or more of the following features. The two opposable legs are stored in a flat, open position. Each of the two opposed legs has an inner facing surface including an adhesive. The strip form unitary body further includes a release liner covering the adhesive. The body of each tab has projections extending from a surface opposite the adhesive and arranged to be engaged by the adhesive of an overlapping layer of the roll, to limit inter-tab adhesion. The body of each tab has a silicone coating on a surface opposite the adhesive and arranged to be engaged by the adhesive of an overlapping layer of the roll, to limit inter-tab adhesion.
Other features and advantages of the invention will be apparent from the following description of embodiments, and from the claims.